Reinforced silica textile



June 30, 1953 PARKER REINFORCED SILICA TEXTILE Filed Sept. 10, 1949 a J. x E,

IN VEN TOR.

ATTORNEY.

Patented June 30, 1953 REINFORCED SILICA TEXTILE Leon Parker, Burbank, Calif., assignor to The H. I. Thompson Company, Los Angeles, Calif., a corporation of California Application September 10, 1949, Serial No. 114,998

(Ci. Z8-78) 21 Claims.

This invention relates to reinforced silica fiber textile material including yarn, thread, rope, braid, and other woven, braided and knitted material in which silica fibers are fabricated into textiles.

It has been recently discovered that ordinary glass fibers usually employed in making glass fiber textiles may be extracted to remove the glass making oxides, other than silica, and to leave a highly siliceous material in which the silica element may run from 90% to over 99+% of the oxide element of the extracted material. The extracted material is hydrated and in firing at high temperature the material is dehydrated and shrunk. Reference may be had to the Nordberg Patent No. 2,461,841 and to application Serial No. 669,098 filed May 11, 1946, by Leon Parker and Alexander Cole, now Patent No. 2,491,761 for details of this process.

This procedure results in a large impairment in the tensile strength of the glass fabric. While careful control of the extraction and the washing process will give silica fabrics of relatively high tensile strength, the resultant tensile strength is at best much lower than that of the original glass fiber material.

I have found that I may increase the tensile strength of the silica textile by reinforcing the textile by incorporating therein a skeleton structure which has a high inherent tensile strength greater than that of the silica fibers. I may thus produce a silica textile of enhanced strength.

Thus I may obtain a knitted or woven material formed of a skeleton of threads of material having a relatively high inherent tensile strength to support the silica fibers. I may use a wire thread or a yarn material having such relatively high tensile strength that when interwoven or inter-knitted with the silica fibers a composite textile will result of improved tensile strength. Thus I may form a composite textile containing glass fibers, of fibers, filaments, thread, cord or yarn of cotton, wool, linen, asbestos or synthetic resin, such as nylon, cellulose acetate, polyamide resins, polyvinyl chloride and polyvinylidene chloride resins, filamentary or metallic wire material, which has a higher tensile strength, flexibility, and abrasion resistance than the silica fibers, which will result in such an improvement in the strength and wearing qualities of the textile.

The difliculty in producing such composite textiles by interweaving the silica fibers and the supporting fibers of higher tensile strength resides in the inherent weakness of the silica fiber in either its hydrated or dehydrated, i. e., fired, state. This weakness, 1. e., low tensile strength,

imposes a severe limitation on the knitting or weaving operation. The thread breaks easily in the process. This makes the production of the composite fabric by Weaving or knitting impracticable. V

I have developed a procedure for making the above composite textile which overcomes this inherent defect. Instead of weaving or knitting the composite textile using the extracted or extracted and fired silica fibers in thread or yarn form, I first form the textile by weaving or knitting the textile using glass fibers and the other filamentary material to be incorporated in the composite textile.

The composite fabric may then be leached to remove from the glass filaments the glass forming oxides other than silica in the usual manner. The composite fiber may then be fired if desired.

The fiber other than glass employed should preferably be immune to chemical or physical attack by the leaching solution in a degree to materially impair its physical or chemical properties.

Thus, if the glass filament is leachable with water as, for example, the alkali bore-silicate glass having a high boron-oxide to alkali ratio, for example, not less than about 5:1, I may employ almost any other filament in forming the original composite glass cloth, for example, any of the filaments referred to above, since they will not be impaired by the water. In fact, most filamentary material, such as is used for weaving, knitting, braiding, cording or other textile forming process, whether metallic or non-metallic, or organic or inorganic, such as the glass, not leachable by water, may be used, since what is desired is a fiber which will not be attacked by water or attack by water will not be significant in re ducing its strength to a relatively low value. I may extract the glass cloth by prolonged attack by water to remove the non-siliceous oxides and thus give a leached composite cloth of higher tensile strength than can be obtained by leaching a textile formed of the leachable glass fibers. When I employ a glass fiber which is leachable with water, I may form a composite fabric formed of water leachable glass and also of glass which is immune to attack by such water. Such glasses are the boro-silicate glasses having 70% or more of SlOz, and if containing less than 70%, those which are substantially free from alkali metal oxides but which contain substantial amounts of second group oxides and alumina or any other type of glass filaments composed of S102 and other water insoluble glass forming oxides.

Where the glass fibers are not leachable by water but require an acid leaching agent, such as l-ICl, as is the case with those glasses the properties of which make them particularly suitable for formation into filaments suitable for textile manufacture and which are now widely used for this purpose, I prefer to use as the added tensile strength-imparting filament material one which is resistant to attack by the acid.

The acid leachable glass fibers are characterized by being formed from boro-silicate glasses substantially free from alkali and containing substantial amounts of second group oxides and alumina, for example, 56% .or less of S102, about 22% or less of second group oxides, .about 12% or more of A1203, and about or more of B203. Soda-lime glasses may also be leached with acid, i. e., those containing about 20% or more of alkali and about 15% or less of SiOz and containing second group oxides.

I have found that for my purposes, because of their adaptability to forming ,glass filaments and textiles, the acid leachable boro-silicate glasses are to be preferred.

I, therefore, incorporate as the addedstrengthimparting filament one whichis resistant to such attack by acid and preferably'by acid at the elevated leaching temperatures employed. 1 Such filaments are the acid resistant glass filaments and acid resistant organic synthetic fibers such as polyvinylidene chloride, polyvinyl chloride, and the non-corrosive metallic wires listed below. All of these materials form a natural grou in that they can be formed into filaments which can be formed into textiles and resistv chemical attack by 1101 at elevated temperatures above 100 F. and below 212 E. which temperatures are usually employed in the glass'leaching operation.

However, if the textile 'is to be fired to -dehydrate it, I must .use as the fiber, other than the leachable glass fiber, a material which will be stable at the elevated firing temperature .of about 750 F. and preferably as high as 1600IF. at which the textile is fired. In such circumstance I cannot use the organic fibers, natural or synthetic, since they will be destroyed by firing and glass filaments will .lose their strength by devitrification or may actually melt if the higher temperatures are used. In such circumstance I prefer to employ filaments of .material which will be stable at the high temperatures used for dehydration and shrinkage of the leached fabrics.

I thus prefer to use the metallic filaments. Many metals are available in fine wire form and may be handled on conventional braiding,.cording, weaving or knitting machines. These include copper, steel, nickel, chromium, nickelmolybdenum, and many others which will suggest themselves to those skilled in this art. However, if the leaching agent be acid, I must select those which are not corroded byacid, and thus I prefer to employ the acid resistant filaments made of Hastelloy B (whose composition is referred to below), platinum, tantalum, phosphorbronze, aluminum-bronze, 'gold, silver, nickelsilver alloy, Everdur, which is acopper, silicon, manganese alloy, copper ranging from 94.9 to 98.25%; silicon 1.5 to 4%; manganese 0.25 to 1.1%, and chromium-copperalloys. The metallic wires which have .a .melting :point .at about 1500 F. or higher .form .asub-group of the acid resistant metallic wire group referred to .above in that they are .not only acid resistant, as derat 4 posite textile is fired or used at temperatures of 1500 F.

I therefore distinguish the filaments employed in my composite textile formed of such interlaced filaments as leachable glass filaments and non-leachable reinforcing filaments, meaning that under the conditions of leachin wherein I extract the non-siliceous glass oxides of the leachable glass to produce silica fibers containing non-siliceous oxides in the ratio of 9:1 or more of silica to non-metallic oxides, the nonleachable fibers will not be attacked in any substantial manner during such leaching, and I refer to the latter as a reinforcing filament in that theproperties of the composite fabric, such as tensile strength and abrasion resistance, are enhanced by their presence in the reinforced fabric above that formed of the siliceous material alone.

The properties of the resultant leached fibers thus formed intoa composite'textile material'include resistanceto acid or water attack. The fired silica'fibers are not attacked by alkali. The fusion and-softening points are'high above 1600 F., depending upon the amount of leaching and the melting and softening points may be as high as 2000 F. or more.

The dried silica fibers (dried below about 385 F.) and un'fired silica fibers have desiccant properties. The fibers are soft, and before and after firing are'soft and silky and resemble silk even more than do the original glass'fibers.

'In order to preserve these qualities in 'atextile so that it will predominantly have the feel and property of the textile'made of silica fibers, particularly where I use a metallic wire or other strength-imparting filament as the supporting means, I may restrict the number of wires or othe non-siliceous filament or extractable glass fibers employed in the original form of the textile'to be extracted'in relation to the number of threads of the extractable glass fibers used in weaving the original composite glass fiber textile, so that the non-extractable filaments are merely a skeleton to support the extractable glass fibers. This will result in a textile which, after'extraction, is predominantly made of silica fibers. 'Depending upon'the method of weaving or knitting, cording 'or braiding, the reinforcing thread'maybe either periodically revealed'on the surface or be entirely hidden. Additionally, the ratio of the reinforcing'threads to the silica (or leachable glass) threads will depend upon the degree of reinforcement desired and upon the properties of the reinforcing filaments.

This invention will be further described by'reference to the drawings, in which Fig. 1 is a somewhat diagrammatic view of a composite fabric such as'may be employed in'my invention;

Fig. 2 is a section taken along line 2-2 of Fig. 1;

Fig. 3 is a section taken along line 33 of Fig. 1;

Fig. 4 is a section taken along line '4-4 of Fig. 1;

Fig. 5 is a section showing the tube after firing;

Fig. 6 is a fragmentary view of a tubular sleeve using the composite fabric before firing;

Fig. 7 is the view of Fig. 6 after firing;

.Fig. 8 is a section taken on 1ine8-8 of Fig. '6;

Fig. 9, is'a section taken on line 9--9 of Fig. 8; and

Fig. 10 is a perspective .vi'ewisomewhat schescribed above, but will be stable when the com; m t c showing .the tubular s ve af fi The composite fabric is woven or knit or otherwise formed of a skeleton of leach-resistant fibers i and the leachable glass fibers 2. Fig. 1 shows the non-leachable filament skeleton and the interwoven leachable glass fibers. It will be observed that the major portion of the surface may be made up of the glass fibers and that the nonleachable fibers, other than leachable glass, appears in a scattered pattern. However, any other proportion of threads may be employed. Usually, however, the leachable glass fibers are formed into yarns of greater diameter than the metallic wires if they are used and even if the same number of threads is used, the exposed area will be in the major part made up of the extractable glass.

As examples of this type of reinforced silicia fiber cloth, the following may be taken as an example, but not as a limitation of the invention.

A tubular braid may be formed using .007 diameter dead soft Hastelloy B wire having the following composition: C, 0.12%; Mo, 26-30%; Fe, 4-770, and Ni, on balance to make 100%. This is braided with glass fiber cloth having yarn .01" in diameter (made of glass fibers each less than .001" in diameter) having the following composition:

The glass fiber had 2.09% organic matter, being the lubricant employed in the weaving. The material was burned off and the loss in weight (2.09%) is here reported as lubricant. The residual 97.91% had the following composition on a lubricant free basis:

Percent F8203 .56 CaO L 15.96 MgO 1.10

NaaO .88

The braidin machine, for example, may have 24 carriers, using 12 carriers of wire and 12 carrier of glass fibers with two ends per carrier and 14 picks per inch. Figs. 1, 2, 3, and 4 illustrate the nature of the knit and the location of the filaments. The sleeving can be leached in 12% Hl solution for two hours at 170 F. and then washed with water until chloride free and until the water had a pH of about 7-8. The wire is not attacked by the acid and no discoloration of the glass cloth results. The leaching operation is conducted until the silica ratio to the remaining non-siliceous oxides is about 9:1 or more and preferably until the total silica content based on the fired dehydrated silica filament is 95 to about 99+%. The undehydrated, leached fibers have the conformation and arrangement of the original fibers of the composite textile, as is illustrated in Figs. 1, 4, 6, and 8. To dehydrate the silica fibers the textile is fired at high temperature, for example, for 20 minutes at 1500 F. Such silica fibers when fired will have the properties referred to above and a melting point in excess of 2000 F. The resultant sleeving which is produced has the characteristic look and feel of sleeving produced when only glass cloth is leached. The revealed wires appear at uniformly spaced points over the surface of the sleeving. The sleeving is many times as strong in tension when compared to a sleeving similarly formed of fine glass fibers but containing no wire. The wires also impart a rigidity to the sleeving not present when no wire is used.

Firing of the sleeving at 1500 F. for 20 minutes results in a shrinkage of the silica fibers but the wires do not shrink. 'As a result the wires, where they are revealed at the surface, appear to be crimped, thus giving a series of hook-like projections 3 standing from the surface. illustrated in Figs. 7, 9, 10. It will be observed that in Figs. 5, 7, 9, and 10 the shrinkage of the silica fibers on dehydration and firing have crimped the wire skeleton, causing it to crinkle and stand above the surface in the form of loops or hooks.

' The siliceous fibers shrink due to the crimping action in the non-shrinkable wire. The wire thus projects through the surface forming a plurality of hook-like members to give a rough, non-slip surface. This phenomenon is observed irrespctive of the form of the textile, whether woven cloth, braided or knitted tape, corded material or knitted or woven sleeving or any other form in which the wire skeleton is employed in a composite fabric in the above procedure.

The resultant fired material in which the hooklike projections are employed may have many uses. It may be used as a heat resistant insulating packing by stacking the material in as a blanket or insulating sheathing, the hooks interlocking and helping to hold the form of the packing. Thus sheets of fired, composite, woven or knit material may be stacked in on top of each other to form a blanket and encased in an envelope of metal foil, the hooks interlocking to hold the sheets in place in the blanket. Such a blanket will have inherent strength and even severe handling will not cause the fragmentation or rupturing of the silica fibers.

Similarly, when tubes are to be stacked intoa honeycomb structure to form a plurality of ducts, the hooks on the surface of the tubes, such as shown in Fig. 10, interlock to hold the tubes in place.

The unfired fabric may be employed where acid.

resistant silica fabric is desired, and if metallic fabric or wires are undesirable, and if the service permits, the non-metallic fibers heretofore suggested to be used in the composite fabric may be employed.

The heat insulating blankets, therefore, will have a superior life over the heat insulating blankets fired at high temperature where silica batts formed of extracted glass fiber batts are employed.

While I have described a particula embodiment of my invention for the purpose of illustration, it should be understood that various modification and adaptations thereof may be made within the spirit of the invention as set forth in the appended claims.

I claim:

1. A textile material formed of silica filaments containing metallic oxides, the silica being in excess of of the silica fibers, and other reinforcing filaments.

2. A textile material formed of silica filaments containing metallic oxides, the silica being in excess of 90% of the silica fibers, and metallic filaments.

3. A method of producing a reinforced silica fiber textile, which comprises interlacing leachable glass fibers with reinforcing fibers, leaching from the leachable glass fibers the non-siliceous glass forming oxides to form silica fibers which contain silica in excess of 90% of said silica fibers This is without substantially attacking the reinforcing fibers.

4. A method of producing a reinforced silica fiber textile, which comprises interlacing leach-- able glass fibers with reinforcing fibers, leaching from the leachable glass fibers the non-siliceous glass forming oxides to form silica fibers which contain silica in excess of 90% of said silica fibers without substantially attacking the reinforcing fibers, and washing and firing the leached fabric.

5. A method of producing a reinforced silica fiber textile, which comprises interlacing leachable glass fibers with reinforcing glass fibers, leaching from the leachable glass fibers the nonsiliceous glass forming oxides to form silica fibers which contain silica in excess of 90% of said silica fibers without substantially attacking the reinforcing glass fibers.

6. A method of producing a reinforced silica fiber textile, which comprises interlacing leachable glass fibers with reinforcing non-siliceous fibers, leaching from the leachable glass fibers the non-siliceous glass forming oxides to form silica fibers Which contain silica in excess of 90% of said silica fibers without substantially attacking the reinforcing non-siliceous fibers.

7. A method of producin a reinforced silica fiber textile, which comprises interlacing leachable glass fibers with reinforcing metallic fibers, leaching from the leachable glass fibers the nonsiliceous glass forming oxides to form silica fibers which contain silica in excess of 90% of said silica fibers Without substantially attacking the reinforcing metallic fibers.

8. A method of producing a reinforced silica fiber textile, which comprises interlacing leachable glass fibers with reinforcing organic fibers, leaching from the leachable glass fibers the nonsiliceous glass forming oxides to form silica fibers which contain silica in excess of 90% of said silica fibers without substantially attacking the reinforcin organic fibers.

9. A textile material formed of interlaced silica filaments and other reinforcing filaments.

10. A textile material formed of interlaced silica filaments and metallic filaments.

11. A textile material formed of interlaced silica filaments and acid resistant metallic filaments.

.12. A textile material formed of interlaced silica filaments and non-leachable glass filaments.

13. A textile material formed of interlaced silica filaments andacid resistant glass filaments.

14. A textile material formed of interlaced silica filaments and organic filaments.

15. A textile material formed of interlaced silica filaments and acid resistant organic filaments.

16. A textile material formed of interlaced silica filaments containing silica in excess of 0f the silica fibers and metallic filaments.

17. A textile material formed of interlaced silica filaments containing silica in excess of 90% of the silica fibers and acid resistant metallic filaments.

18. A textile material formed of interlaced silica filaments containing silica in excess of 90% of the silica fibers and non-leachable glass filaments. v

19. A textile material formed of interlaced silica filament containing silica in excess of 90% of the silica fibers and acid resistant glass filaments.

20. A textile material formed of interlaced silica filaments containing silica in excess of 90% of the silica fibers and organic filaments.

21. A textile material formed of interlaced silica filaments containing silica in excess of 90% of the silica fibers and acid resistant organic filaments.

LEON PARKER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,132,702 Simpson Oct. 11, 1938 2,133,237 Slayter Oct. 11, 1938 2,135,057 Slayter Nov. 1, 1938 2,261,148 Ebaugh Nov. 4, 1941 2,350,504 Geier June 6, 1944 2,458,243 Biddle Jan. 4, 1949 2,461,841 Nordberg Feb. 15, 1949 2,491,761 Parker Dec. 20, 1949 

9. A TEXTILE MATERIAL FORMED OF INTERLACED SILICA FILAMENTS AND OTHER REINFORCING FILAMENTS. 